The present invention relates to a control apparatus of a powertrain of a vehicle etc., particularly to a control apparatus of a powertrain having a centrifugal pendulum absorber.
Conventionally, to improve fuel efficiency of engines of vehicles mounted with a powertrain forming a drive force transmission path which is from the engine to drive wheels via an automatic transmission, it is known to apply a reduced-cylinder operation, a homogeneous charge compression ignition (HCCI) combustion of the engine, and further omission of a torque converter from the automatic transmission, etc.
However, with such an engine adopting the reduced-cylinder operation and/or the HCCI combustion, the output torque thereof tends to vary greatly. With the omission of the torque converter from the automatic transmission, the torque variation of the engine is outputted as-is without attenuating. Thus, in the vehicles applied with theses arts, the variation in torque transmitted to a drive force transmission system on an output side of the automatic transmission becomes large. Especially if torsional vibration caused by the torque variation is amplified by resonance of the drive force transmission system, vibration and noise may occur in various parts of the vehicle.
For this, an art of communicating a centrifugal pendulum absorber with a drive force transmission shaft so as to reduce vibration is known (e.g., JP2014-228009A). The centrifugal pendulum absorber includes a support member for rotating together with the drive force transmission shaft, and a pendulum (mass body) supported by the support member to be swingable with respect to a point on a circumference of a circle with a given radius centering on an axial center of the support member.
Here, within a low engine speed range applied when the engine starts etc., the centrifugal pendulum absorber communicated with the drive force transmission shaft rotates at a low speed, and a centrifugal force which acts on the pendulum becomes small. Therefore, the operation of the pendulum to reduce the torque variation by using the centrifugal force becomes unstable, and an abnormal sound may occur by being brought into contact with a peripheral member. In order to reduce the abnormal sound, in the invention of JP2014-228009A, a connect-disconnect mechanism for cutting off drive force transmission to the centrifugal pendulum absorber within the low engine speed range is disposed between the drive force transmission shaft and the centrifugal pendulum absorber. The connect-disconnect mechanism in this specification is a frictional engagement type clutch which transmits a drive force with a friction force, and even if there is a difference in rotational speed between an input shaft and an output shaft thereof, the clutch is capable of smoothly transmitting a torque by shifting itself from a released state to one of a slip state and an engaged state while adjusting a tightness of the engagement by a hydraulic or current control. Note that the words “engagement” and “release” in this specification mean general connection and disconnection of the connect-disconnect mechanism, and the word “slip” means an incomplete connection where the connect-disconnect mechanism slips.
Here, with the connect-disconnect mechanism between the drive force transmission shaft and the centrifugal pendulum absorber similarly to the conventional art of JP2014-228009A, since the torque variation is large during the reduced-cylinder operation as described above, it is considered to let the centrifugal pendulum absorber exert the vibration reducing function when the engine shifts from an all-cylinder operation to the reduced-cylinder operation, by outputting an engaging command to shift the connect-disconnect mechanism from the released state to the engaged state simultaneously with an output of a cylinder reduction (suspension) command.
However, if the connect-disconnect mechanism is especially a hydraulic type, the engagement or release of the connect-disconnect mechanism is generally delayed with respect to the shifting of the operating state of the engine. Therefore, when the engine shifts from the all-cylinder operation to the reduced-cylinder operation in which the vibration reduction by the centrifugal pendulum absorber is requested, the engagement of the connect-disconnect mechanism does not complete even after the engine shifted to the reduced-cylinder operation, and during this time, the torque variation of the engine cannot be reduced by the centrifugal pendulum absorber, and the vibration problem described above may arise.
Further, when the engine shifts from the reduced-cylinder operation to the all-cylinder operation, if the release of the connect-disconnect mechanism delays, especially when an acceleration request is issued by depression of an acceleration pedal, acceleration of the vehicle may be interrupted by an inertia moment (inertia) of the centrifugal pendulum absorber which acts on the drive force transmission shaft as a load moment.